* In September 2014, X broke, and I created an `/etc/X11/Xwrapper.config` file with the lines `allowed_users = anybody` and `needs_root_rights = yes` to get it to work again. I don't remember and don't have notes on why that helped. It sure does sound like a pretty terrible hack. I don't have that Xwrapper.config file anymore, and I also don't know when I deleted it.
* In June 2017, audio stopped working, but all I had to do was add my user to the `audio` group.
* In May 2018, X broke a second time. This time I downgraded the `xorg-server-common` and `xorg-server` packages. A few weeks later, I ran another system upgrade, and this one went fine.
These weren't the only problems, but they were the most disruptive. Generally, things like TrackPoint driver updates changing how the cursor responds or Firefox changing its UI have been far more annoying than Arch Linux issues :)